Structural reliability for the design of rack columns using the Direct Strength Method

Resumo

Cold-formed steel profiles have been increasingly used in civil engineering applications. A very
common section of cold formed profiles is the rack section, mainly used in industrial storage systems. In a few
situations, rack profiles present repeated perforations along the length of the member to provide greater freedom
of assembly. The structural design standards need to ensure that profiles used in these conditions guarantee the
required safety. This work aimed to evaluate the reliability indexes (β) of perforated rack profiles under axial
compressive load, using the FOSM and FORM reliability methods and the Monte Carlo Simulation (MCS). In
order to obtain the professional factor (P), a database of experimental tests from several authors was elaborated,
to be compared to three proposals for adapting the Direct Strength Method (DSM) to perforated columns. The
reliability indexes were calculated for the load combinations of AISI S100 (2016) and NBR 14762 (2010)
specifications. The β values obtained using two of the methodologies were shown far from the 2.5 and 3.0
calibration targets. The β values obtained by the third methodology were close to the 2.5 target. The last method
proved to be the safest, although it requires the Form Factor (Q), that needs to be obtained experimentally.